194809981 has 4 divisors (see below), whose sum is σ = 194867964. Its totient is φ = 194752000.

The previous prime is 194809961. The next prime is 194809991. The reversal of 194809981 is 189908491.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 157904356 + 36905625 = 12566^2 + 6075^2 .

It is a cyclic number.

It is not a de Polignac number, because 194809981 - 2⁹ = 194809469 is a prime.

It is a super-2 number, since 2×194809981² = 75901857394440722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (194809961) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23620 + ... + 30781.

It is an arithmetic number, because the mean of its divisors is an integer number (48716991).

Almost surely, 2^194809981 is an apocalyptic number.

It is an amenable number.

194809981 is a deficient number, since it is larger than the sum of its proper divisors (57983).

194809981 is an equidigital number, since it uses as much as digits as its factorization.

194809981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57982.

The product of its (nonzero) digits is 186624, while the sum is 49.

The square root of 194809981 is about 13957.4346138537. The cubic root of 194809981 is about 579.7005796982.

The spelling of 194809981 in words is "one hundred ninety-four million, eight hundred nine thousand, nine hundred eighty-one".